Question

lanthanide element has maximum abundance in earth crust

Answer 1

the lanthanides are known to have abundances comparable to many other elements. The 15 elements, together with their chemical symbols, are lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Thulium, one of the scarcest lanthanides, has an abundance in the earth's crust of 0.2 parts per million (ppm), and is more abundant than arsenic or mercury. The most abundant is cerium (46 ppm), which is more abundant than tin. Promethium, which is radioactive, is found only in trace amounts in uranium ores. Small amounts have been isolated from the spent fuel of nuclear reactors. The lanthanide elements, cerium through lutetium, have corresponding atomic numbers of 58 through 71.